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Research & Scholarship

Current Research and Scholarly Interests

Our laboratory focuses on two interrelated projects: (1) assessment of glioma development within the framework of the multistage model of carcinogenesis through utilization of the rodent model of ENU neurocarcinogenesis; and (2) assessment of stem cell specification and pluripotency using an embryonic stem cell model system in which neural differentiation is induced.

Clinical Trials

This, international, multi-center, Phase 2 study of verubulin will be conducted in patients
with newly diagnosed Glioblastoma Multiforme (GBM). The study will be conducted in two
parts. Part A is an open-label dose finding study that will determine the safety and
tolerability of verubulin in combination with standard treatment. Part B is a randomized
open-label study that will investigate progression-free survival and overall survival of
patients receiving verubulin, at the dose determined in Part A, in combination with standard
treatment versus standard treatment alone.

Stanford is currently not accepting patients for this trial.For more information, please contact Cathy Recht, (650) 725 - 8630.

A Study to Evaluate the Safety and Antitumor Activity in Subjects With Advanced Solid TumorsRecruiting

To determine the maximum tolerated dose or optimal biological dose, and the safety profile
of MEDI3617 when given as a single-agent or in combination with other chemotherapeutic
agents in subjects with advanced solid malignancies resistant to standard therapy.

The purpose of this study is to investigate the safety and effectiveness of a combination
treatment for glioblastoma multiforme utilizing radiotherapy with the FDA approved
chemotherapy drug temozolomide

An Open-Labeled, Extended-Use of XERECEPT (hCRF) for Patients in Studies NTI 0302, 0303, or Other Designated StudiesNot Recruiting

The purpose of this study is to examine the long-term safety and tolerability of human
corticotropin-releasing factor (hCRF), XERECEPT®, in patients requiring dexamethasone
(Decadron) to treat peritumoral brain edema. This open-label, extended-use study is open to
all patients who participate in either of the blinded studies, NTI 0302, NTI 0303, or other
designated studies, including patients who may have discontinued blinded study medication
early but completed the protocol-stipulated follow-up periods.

Stanford is currently not accepting patients for this trial.For more information, please contact Lynn Adler, (650) 725 - 8630.

To investigate the safety of delivering arsenic trioxide (ATO) in combination with
stereotactic radiotherapy in recurrent malignant glioma by performing an open label, Phase I
dose escalation trial. Results from this study will provide a basis for further study of ATO
combined with radiation therapy as a radiosensitizer for malignant brain tumors in future
Phase II studies.

Stanford is currently not accepting patients for this trial.For more information, please contact Laurie Tupper, (650) 498 - 4143.

This 2-arm, randomized, phase III study will investigate the efficacy and safety of the
addition of rindopepimut (an experimental cancer vaccine that may act to promote anti-cancer
effects in patients who have tumors that express the EGFRvIII protein) to the current
standard of care (temozolomide) in patients with recently diagnosed glioblastoma, a type of
brain cancer.
All patients will be administered temozolomide, the standard treatment for glioblastoma.
Half the patients will be randomly assigned to receive rindopepimut and half the patients
will be randomly assigned to receive a control called keyhole limpet hemocyanin.
Patients will be treated in a blinded fashion (neither the patient or the doctor will know
which arm of the study the patient is on). Patients will be treated until disease
progression or intolerance to therapy and all patients will be followed for survival.

Stanford is currently not accepting patients for this trial.For more information, please contact Vani Jain, 650-723-1005.

A Study of Onartuzumab (MetMAb) in Combination With Bevacizumab Compared to Bevacizumab Alone or Onartuzumab Monotherapy in Patients With Recurrent GlioblastomaNot Recruiting

This randomized, double-blind, placebo-controlled, multicenter phase II study will evaluate
the safety and efficacy of onartuzumab (MetMAb) in combination with bevacizumab as compared
to bevacizumab alone and of onartuzumab as monotherapy in patients with recurrent
glioblastoma. Patients will be randomized 1:1:1 to receive either placebo plus bevacizumab
every 3 weeks, or onartuzumab plus bevacizumab, or onartuzumab plus placebo. Anticipated
time on study treatment is until disease progression or unacceptable toxicity occurs.

Stanford is currently not accepting patients for this trial.For more information, please contact Sophie Bertrand, (650) 723 - 4467.

This is a pilot imaging study for women whose tumors express NIS [Na+I- symporter, sodium
iodide symporter]. Eligibility is limited to the presence of strong (3+) and/or plasma
membrane staining in > 20% of cells as determined by immunohistochemical methods. A total of
10 patients will be imaged with 124I PET/CT (serial scans over 24 hour period) to determine
radioiodide uptake and distribution in tumor tissue. Thyroid iodide uptake and retention
will be blocked beginning one week prior to 124I PET/CT scan with thyroid hormone (T3) and
methimazole (impedes organification). Tumor, organ and whole body dosimetry will be
calculated in each patient.

Stanford is currently not accepting patients for this trial.For more information, please contact Marilyn Florero, (650) 724 - 1953.

A Study of MEDI-575 in Subjects With Recurrent Glioblastoma MultiformeNot Recruiting

The primary objective of this Phase II study is to evaluate the progression-free survival at
6 months in adult subjects with a first recurrence of Glioblastoma Multiforme who are
treated with MEDI-575.

Stanford is currently not accepting patients for this trial.For more information, please contact Cathy Recht, (650) 725 - 8630.

High Grade Gliomas, including anaplastic astrocytomas, anaplastic oligodendrogliomas and
glioblastomas (GBM), are the most common and most aggressive primary brain tumors. Prognosis
for patients with high-grade gliomas remains poor. The estimated median survival for
patients with GBM is between 12 to 18 months. Recurrence after initial therapy with
temozolomide and radiation is nearly universal. Since May 2009, the majority of patients in
the US with an initial recurrence of high-grade glioma receive bevacizumab, a monoclonal
antibody against vascular endothelial growth factor (VEGF), which is thought to prevent
angiogenesis in these highly vascular tumors. BEV has response rates from 32-62% and has
improved overall median survival in patients with recurrent high-grade gliomas1. However,
the response is short lived, and nearly 100% of patients eventually progress despite
bevacizumab. No chemotherapeutic agent administered following progression through
bevacizumab has made a significant impact on survival. Patients progress to death within 1-5
months after resistance develops. Therefore, patients with high-grade gliomas who have
progressed through bevacizumab represent a population in dire need of a feasible and
tolerable treatment.
NKTR-102 is a topoisomerase I inhibitor polymer conjugate that was engineered by attaching
irinotecan molecules to a polyethylene glycol (PEG) polymer using a biodegradable linker.
Irinotecan released from NKTR-102 following administration is further metabolized to the
active metabolite, 7-ethyl-10-hydroxy-camptothecin (SN38), that causes DNA damage through
inhibition of topoisomerase. The goal in designing NKTR-102 was to attenuate or eliminate
some of the limiting side effects of irinotecan while improving efficacy by modifying the
distribution of the agent within the body. The size and structure of NKTR-102 results in
marked alteration in pharmacokinetic (PK) profile for the SN38 derived from NKTR-102
compared to that following irinotecan: the maximal plasma concentration (Cmax) is reduced 5-
to 10-fold and the half-life (t1/2 ) of SN38 is increased from 2 days to approximately 50
days. This altered profile leads to constant exposure of the tumor to the active drug. In
addition, the large NKTR-102 molecule does not freely pass out of intact vasculature, which
may account for relatively higher concentrations of the compound and the active metabolites
in tumor tissues in in vivo models, where the local vasculature may be relatively more
permeable. A 145 mg/m2 dose of NKTR-102, the dose intended for use in this phase II clinical
trial (and being used in the phase III clinical program), results in approximately the same
plasma exposure to SN38 as a 350 mg/m2 dose of irinotecan, but exposure is protracted,
resulting in continuous exposure between dosing cycles and lower Cmax. NKTR-102 was
therefore developed as a new chemotherapeutic agent that may improve the clinical outcomes
of patients.

Stanford is currently not accepting patients for this trial.For more information, please contact Cathy Recht, (650) 725 - 8630.

The purpose of this study is to examine the safety and efficacy of XERECEPT (human
Corticotropin-Releasing Factor, or hCRF) compared to dexamethasone in patients with primary
malignant glioma who require increased dexamethasone doses to control symptom of peritumoral
brain edema.

Stanford is currently not accepting patients for this trial.For more information, please contact Cathy Recht, (650) 725 - 8630.

The purpose of this study is to compare the safety and efficacy of XERECEPT® to
dexamethasone (Decadron) a common treatment for symptoms of brain swelling (edema). This
study is specifically aimed at patients who require chronic high doses of dexamethasone to
manage symptoms.

Stanford is currently not accepting patients for this trial.For more information, please contact Lynn Adler, (650) 725 - 8630.

18F FPPRGD2 PET/CT or PET/MRI in Predicting Early Response in Patients With Cancer Receiving Anti-Angiogenesis TherapyRecruiting

The purpose of the study is to conduct research of a new PET radiopharmaceutical in cancer
patients. We will assess the uptake of this novel radiopharmaceutical in subjects with
breast cancer, lung cancer, glioblastoma multiforme (GBM) and other cancers requiring
antiangiogenesis treatment.

This study is designed to evaluate the clinical activity of CDX-110 vaccination when given
with standard of care treatment (maintenance temozolomide therapy). Study treatment will be
given until disease progression and patients will be followed for long-term survival
information. Efficacy will be measured by the progression-free survival status at 5.5
months from the date of first dose.

Stanford is currently not accepting patients for this trial.For more information, please contact Cathy Recht, (650) 725 - 8630.

Abstract

The purpose of this study was to estimate magnetic resonance imaging-based brain perfusion parameters from combined multiecho spin-echo and gradient-echo acquisitions, to correct them for T1-, T2-, and -related contrast agent (CA) extravasation effects, and to simultaneously determine vascular permeability. Perfusion data were acquired using a combined multiecho spin- and gradient-echo (SAGE) echo-planar imaging sequence, which was corrected for CA extravasation effects using pharmacokinetic modeling. The presented method was validated in simulations and brain tumor patients, and compared with uncorrected single-echo and multiecho data. In the presence of CA extravasation, uncorrected single-echo data resulted in underestimated CA concentrations, leading to underestimated single-echo cerebral blood volume (CBV) and mean transit time (MTT). In contrast, uncorrected multiecho data resulted in overestimations of CA concentrations, CBV, and MTT. The correction of CA extravasation effects resulted in CBV and MTT estimates that were more consistent with the underlying tissue characteristics. Spin-echo perfusion data showed reduced large-vessel blooming effects, facilitating better distinction between increased CBV due to active tumor progression and elevated CBV due to the presence of cortical vessels in tumor proximity. Furthermore, extracted permeability parameters were in good agreement with elevated T1-weighted postcontrast signal values.

Abstract

The metabolic phenotype that derives disproportionate energy via glycolysis in solid tumors, including glioma, leads to elevated lactate labeling in metabolic imaging using hyperpolarized [1-(13)C]pyruvate. Although the pyruvate dehydrogenase (PDH)-mediated flux from pyruvate to acetyl coenzyme A can be indirectly measured through the detection of carbon-13 ((13)C)-labeled bicarbonate, it has proven difficult to visualize (13)C-bicarbonate at high enough levels from injected [1-(13)C]pyruvate for quantitative analysis in brain. The aim of this study is to improve the detection of (13)C-labeled metabolites, in particular bicarbonate, in glioma and normal brain in vivo and to measure the metabolic response to dichloroacetate, which upregulates PDH activity.An optimized protocol for chemical shift imaging and high concentration of hyperpolarized [1-(13)C]pyruvate were used to improve measurements of lactate and bicarbonate in C6 glioma-transplanted rat brains. Hyperpolarized [1-(13)C]pyruvate was injected before and 45 min after dichloroacetate infusion. Metabolite ratios of lactate to bicarbonate were calculated to provide improved metrics for characterizing tumor metabolism.Glioma and normal brain were well differentiated by lactate-to-bicarbonate ratio (P = .002, n = 5) as well as bicarbonate (P = .0002) and lactate (P = .001), and a stronger response to dichloroacetate was observed in glioma than in normal brain.Our results clearly demonstrate for the first time the feasibility of quantitatively detecting (13)C-bicarbonate in tumor-bearing rat brain in vivo, permitting the measurement of dichloroacetate-modulated changes in PDH flux. The simultaneous detection of lactate and bicarbonate provides a tool for a more comprehensive analysis of glioma metabolism and the assessment of metabolic agents as anti-brain cancer drugs.

Abstract

To compare the safety and efficacy of corticorelin acetate (CrA) and placebo in patients with malignant brain tumors requiring chronic administration of dexamethasone (DEX) to control the signs and symptoms of peritumoral brain edema (PBE).Prospective, randomized, double-blind study of 200 patients with PBE on a stable dose of DEX. Initially, DEX dose was decreased by 50% over a 2-week period and then held at this level for 3 weeks. The primary end point was the proportion of patients who responded to treatment-patients who achieved a ≥ 50% DEX reduction from baseline and achieved stable or improved neurologic examination score and Karnofsky performance score at week 2, and then continued to respond at week 5.One hundred patients received subcutaneous injections of 1 mg twice per day of CrA and 100 patients received placebo for the duration of the study period. Although results did not attain statistical significance (at the P < .05 level), a clinically important difference in the proportion of responders between the CrA group (57.0%) and the placebo group (46.0%; P = .12) was observed. In addition, the maximum percent reduction in DEX dose achieved during the double-blind 12-week study was significantly greater in the CrA group (62.7%) than in placebo group (51.4%; P < .001). Patients receiving CrA demonstrated an improvement in myopathy and were less likely to develop signs of Cushing syndrome.CrA enables a reduction in steroid requirement for patients with PBE and is associated with a reduction in the incidence and severity of common steroid adverse effects, including myopathy.

Abstract

Osteopontin (OPN), which is highly expressed in malignant glioblastoma (GBM), possesses inflammatory activity modulated by proteolytic cleavage by thrombin and plasma carboxypeptidase B2 (CPB2) at a highly conserved cleavage site. Full-length OPN (OPN-FL) was elevated in cerebrospinal fluid (CSF) samples from all cancer patients compared with noncancer patients. However, thrombin-cleaved OPN (OPN-R) and thrombin/CPB2-double-cleaved OPN (OPN-L) levels were markedly increased in GBM and non-GBM gliomas compared with systemic cancer and noncancer patients. Cleaved OPN constituted ∼23 and ∼31% of the total OPN in the GBM and non-GBM CSF samples, respectively. OPN-R was also elevated in GBM tissues. Thrombin-antithrombin levels were highly correlated with cleaved OPN, but not OPN-FL, suggesting that the cleaved OPN fragments resulted from increased thrombin and CPB2 in this extracellular compartment. Levels of VEGF and CCL4 were increased in CSF of GBM and correlated with the levels of cleaved OPN. GBM cell lines were more adherent to OPN-R and OPN-L than OPN-FL. Adhesion to OPN altered gene expression, in particular genes involved with cellular processes, cell cycle regulation, death, and inflammation. OPN and its cleaved forms promoted motility of U-87 MG cells and conferred resistance to apoptosis. Although functional mutation of the RGD motif in OPN largely abolished these functions, OPN(RAA)-R regained significant cell binding and signaling function, suggesting that the SVVYGLR motif in OPN-R may substitute for the RGD motif if the latter becomes inaccessible. OPN cleavage contributes to GBM development by allowing more cells to bind in niches where they acquire anti-apoptotic properties.

Advances in the management of glioblastoma: the role of temozolomide and MGMT testing.Clinical pharmacology : advances and applicationsThomas, R. P., Recht, L., Nagpal, S.2013; 5: 1-9

Abstract

Glioblastoma (GB) is one of the most lethal forms of cancer, with an invasive growth pattern that requires the use of adjuvant therapies, including chemotherapy and radiation, to prolong survival. Temozolomide (TMZ) is an oral chemotherapy with a limited side effect profile that has become the standard of care in GB treatment. While TMZ has made an impact on survival, tumor recurrence and TMZ resistance remain major challenges. Molecular markers, such as O6-methylguanine-DNA methyltransferase methylation status, can be helpful in predicting tumor response to TMZ, and therefore guides clinical decision making. This review will discuss the epidemiology and possible genetic underpinnings of GB, how TMZ became the standard of care for GB patients, the pharmacology of TMZ, the practical aspects of using TMZ in clinic, and how molecular diagnostics - particularly the use of O6-methylguanine-DNA methyltransferase status - affect clinical management.

Abstract

Understanding the early relationship between brain tumor cells and their environment could lead to more sensitive biomarkers and new therapeutic strategies. We have been using a rodent model of neurocarcinogenesis in which all animals develop brain tumors by six months of age to establish two early landmarks in glioma development: the appearance of a nestin(+) cell at thirty days of age and the appearance of cellular hyperplasia between 60 and 120 days of age. We now report an assessment of the CSF proteome to determine the changes in protein composition that occur during this period.Nestin(+) cell clusters and microtumors were assessed in 63 ethylnitrosourea-exposed rats on 30, 60, and 90 days of age. CSF was obtained from the cisterna magna from 101 exposed and control rats at 30, 60, and 90 days and then analyzed using mass spectrometry. Differentially expressed peaks were isolated and identified.Nestin(+) cells were noted in all ethylnitrosourea-exposed rats assessed pathologically. Small microtumors were noted in 0%, 18%, and 67% of 30-, 60-, and 90-day old rats, respectively (p<0.05, Chi square). False Discovery Rate analysis of peak intensities showed that the number of true discoveries with p<0.05 increased markedly with increasing age. Isolation and identification of highly differentially detected proteins at 90 days of age revealed increases in albumin and a fragment of ?1 macroglobulin and alterations in glutathionylated transthyretin.The presence of increased albumin, fragments of cerebrospinal fluid proteins, and glutathione breakdown in temporal association with the development of cellular hyperplasia, suggests that, similar to many other systemic cancers, inflammation and oxidative stress is playing an important early role in the host's response to brain tumor development and may be involved in affecting the early growth of brain tumor.

Abstract

Thermal stability signatures of complex molecule interaction in biological fluids can be measured using a new approach called differential scanning calorimetry (DSC). The thermal stability of plasma proteome has been described previously as a method of producing a disease-specific "signature," termed thermogram, in several neoplastic and autoimmune diseases. We describe the preliminary use of DSC performed on cerebrospinal fluid (CSF) as a diagnostic tool for the identification of patients with glioblastoma multiforme (GBM). Samples of CSF from nine patients with confirmed GBM were evaluated using DSC, and the thermogram signatures evaluated. These thermograms were compared with thermograms of CSF taken from patients with non-neoplastic conditions such as head trauma, hydrocephalus, or CSF leak. Further analysis was also performed on CSF from patients who had non-GBM neoplastic conditions such as carcinomatosis meningitis or central nervous system lymphoma or leukemia. The DSC thermograms of CSF of the patients with GBM were significantly different when compared with other neoplastic and non-neoplastic cases. The melting temperature of the major transition was shifted by 5°C, which makes it easily distinguishable from control cases. Our results are very preliminary, but it appears that the DSC of CSF has potential utility in diagnostics and monitoring disease progression in GBM patients.

Abstract

Chemerin is a chemoattractant involved in immunity that may also function as an adipokine. Chemerin circulates as an inactive precursor (chem163S), and its activation requires proteolytic cleavages at its C terminus, involving proteases involved in coagulation, fibrinolysis, and inflammation. However, the key proteolytic steps in prochemerin activation in vivo remain to be established. Previously, we have shown that C-terminal cleavage of chem163S by plasmin to chem158K, followed by a carboxypeptidase cleavage, leads to the most active isoform, chem157S. To identify and quantify the in vivo chemerin isoforms in biological specimens, we developed specific ELISAs for chem163S, chem158K, and chem157S, using antibodies raised against peptides from the C terminus of the different chemerin isoforms. We found that the mean plasma concentrations of chem163S, chem158K, and chem157S were 40 ± 7.9, 8.1 ± 2.9, and 0.7 ± 0.8 ng/ml, respectively. The total level of cleaved and noncleaved chemerins in cerebrospinal fluids was ?10% of plasma levels whereas it was elevated ?2-fold in synovial fluids from patients with arthritis. On the other hand, the fraction of cleaved chemerins was much higher in synovial fluid and cerebrospinal fluid samples than in plasma (?75%, 50%, and 18% respectively). Chem158K was the dominant chemerin isoform, and it was not generated by ex vivo processing, indicating that cleavage of prochemerin at position Lys-158, whether by plasmin or another serine protease, represents a major step in prochemerin activation in vivo. Our study provides the first direct evidence that chemerin undergoes extensive proteolytic processing in vivo, underlining the importance of measuring individual isoforms.

Abstract

OPINION STATEMENT: Central nervous system (CNS) involvement is a serious, and frequently fatal, complication of acute leukemias and very aggressive lymphomas. In patients with no evidence of CNS involvement at the time of diagnosis, the decision to include CNS prophylaxis in the treatment regimen should be based on cytologic diagnosis and other risk factors. Patients with a risk of CNS relapse greater than 10% should receive CNS prophylaxis with high-dose systemic chemotherapy, intrathecal therapy, radiation, or a combination thereof. The most commonly used systemic and intrathecal chemotherapies are methotrexate and cytarabine. Liposomal cytarabine, which increases CNS bioavailability and decreases the number of lumbar punctures needed, is our preference for intrathecal therapy. We usually reserve radiation therapy for patients who may not tolerate other forms of CNS prophylaxis. Patients with evidence of CNS involvement, either at diagnosis or relapse, should be treated until CNS disease clearance or dose-limiting toxicity is reached. Recent studies suggest that autologous stem cell transplantation may offer longer survivals for patients with CNS involvement and should be considered for patients who can tolerate the procedure. The use of rituximab in CNS prophylaxis and treatment has not yet been clearly delineated, but initial reports indicate that this agent and others may soon be available as an effective and tolerable CNS-directed therapy for lymphomas.

Abstract

We found that adenosine 5'-monophosphate-activated protein kinase (AMPK), which is considered the "fuel sensor" of mammalian cells because it directly responds to the depletion of the fuel molecule ATP, is strongly activated by tumor-like hypoxia and glucose deprivation. We also observed abundant AMPK activity in tumor cells in vivo, using subcutaneous tumor xenografts prepared from cells transformed with oncogenic H-Ras. Such rapidly growing transplants of tumor cells, however, represent fully developed tumors that naturally contain energetically stressed microenvironments that can activate AMPK. Therefore, to investigate the induction of AMPK activity during experimental tumorigenesis, we used an established model of brain tumor (glioma) development in the offspring of rats exposed prenatally to the mutagen N-ethyl-N-nitrosourea. We observed that immunostaining for a specific readout of AMPK activity (AMPK-dependent phosphorylation of acetyl-CoA carboxylase) was prominent during N-ethyl-N-nitrosourea-initiated neurocarcinogenesis, from the occurrence of early hyperplasia (microtumors) to the emergence of large gliomas. Moreover, we observed that immunostaining for activating phosphorylation of AMPK correlated with the same stages of glioma development, notably in mitotic tumor cells in which the signal showed punctate as well as cytoplasmic patterns associated with spindle formation. Based on these observations, we propose that neurocarcinogenesis requires AMPK-dependent regulation of cellular energy metabolism.

Bevacizumab improves quality of life in patients with recurrent glioblastoma.Chemotherapy research and practiceNagpal, S., Harsh, G., Recht, L.2011; 2011: 602812-?

Abstract

Objective. To quantify the benefits in survival and quality of life in patients receiving bevacizumab (BEV) for recurrent glioblastoma (GBM). Methods. This is a retrospective study of 40 adult patients with recurrent GBM treated between 2005 and 2009 at a single institution. All patients had initial treatment with surgery, radiation, and concurrent temozolomide, then monthly temozolomide. Over 250 charts were screened. Sufficient data was available for 20 patients treated with BEV and 20 patients who did not receive BEV at the time of recurrence. The independent living score (ILS), designed to reward long-term independent survival, was calculated for each patient. Results. The mean ILS was nearly double in the BEV group compared to the No-BEV group (15.0 versus 8.2, P = 0.002, t-test). Two months after initiation of therapy, the median steroid dose dropped by over 90% in patients treated with BEV, but doubled in the NoBEV group. Median survival from the time of recurrence was significantly affected: 10.6 months in the BEV group versus 4.2 months (P < 0.001, log rank survival) in the NoBEV group. Conclusions. BEV increases independent living and lengthens overall survival after GBM recurrence. Reduction in steroid dose may contribute to prolonged independence.

Abstract

Central nervous system (CNS) involvement in non-Hodgkin lymphoma is a serious, potentially preventable complication that can occur in 5 to 10% of patients. Its occurrence is directly correlated with pathologic aggressiveness and ranges from less than 3% in the indolent, less-aggressive histologies to as high as 50% in the very aggressive ones such as Burkitt lymphoma. Aggressive treatment once detected can improve neurologic outcome, but because it is often associated with contemporaneous systemic relapse, is rarely associated with long-term survival. Preventing its occurrence, therefore, remains an important goal of initial treatment. Despite there being some suggestive evidence that the addition of systemic rituximab and several intracerebrospinal fluid chemotherapy regimens may have decreased the incidence of CNS involvement, both optimal selection of those patients who should receive prophylaxis as well as the best prophylactic regimen remain active areas of investigation.

Abstract

Although embryonic stem (ES) cells have been induced to differentiate into diverse neuronal cell types, the production of cortical projection neurons with the correct morphology and axonal connectivity has not been demonstrated. Here, we show that in vitro patterning is critical for generating neural precursor cells (ES-NPCs) competent to form cortical pyramidal neurons. During the first week of neural induction, these ES-NPCs begin to express genes that are specific for forebrain progenitors; an additional week of differentiation produces mature neurons with many features of cortical pyramidal neurons. After transplantation into the murine cerebral cortex, these specified ES-NPCs manifest the correct dendritic and axonal connectivity for their areal location. ES-NPCs transplanted into the deep layers of the motor cortex differentiate into layer 5 pyramidal neurons and extend axons to distant subcortical targets such as the pons and as far caudal as the pyramidal decussation and descending spinal tract and, importantly, do not extend axons to inappropriate targets such as the superior colliculus (SC). ES-NPCs transplanted into the visual cortex extend axons to the dorsal aspect of the SC and pons but avoid ventral SC and the pyramidal tract, whereas cells transplanted deep into the somatosensory cortex project axons to the ventral SC, avoiding the dorsal SC. Thus, these data establish that ES-derived cortical projection neurons can integrate into anatomically relevant circuits.

Abstract

Life-threatening illness creates severe stress that may result in marital discord, separation, or divorce and may adversely impact treatment, quality of life, and survival. The few studies that are available to date have suggested that the risk of divorce is not higher in cancer patients, but to the authors' knowledge, no data exist to date that have examined the effect of gender on this rate.A total of 515 patients were prospectively identified as having either a malignant primary brain tumor (N = 214), a solid tumor with no nervous system involvement (N = 193), or multiple sclerosis (N = 108) who were married at the time of diagnosis. Basic demographic information and data regarding marital status were compiled. Patients were followed prospectively from enrollment until death or study termination.Women composed 53% of the patient population. Divorce or separation occurred at a rate similar to that reported in the literature (11.6%). There was, however, a greater than 6-fold increase in risk after diagnosis when the affected spouse was the woman (20.8% vs 2.9%; P < .001). Female gender was found to be the strongest predictor of separation or divorce in each cohort. Marriage duration at the time of illness was also correlated with separation among brain tumor patients (P = .0001). Patients with brain tumors who were divorced or separated were more likely to be hospitalized, and less likely to participate in a clinical trial, receive multiple treatment regimens, complete cranial irradiation, or die at home (P < .0001).Female gender was found to be a strong predictor of partner abandonment in patients with serious medical illness. When divorce or separation occurred, quality of care and quality of life were adversely affected.

Abstract

Glioblastoma multiforme (GBM), the most common malignant primary brain tumor in adults, carries a poor prognosis, with median survival generally less than 1 year. Although initial therapy often eradicates the bulk of the tumor, disease recurrence, usually within 2 cm of the original tumor, is almost inevitable. This may be due to a failure of current therapies to eradicate viable chemotherapy- and radiotherapy-resistant neoplastic progenitor cells, which may then repopulate tumors. An increasing body of preclinical data suggests that these cells may correspond to stem cells derived from the subventricular zone (SVZ), which migrate to tumor sites and contribute to glioma growth and recurrence. Therapeutic targeting of SVZ stem cell populations via cerebrospinal fluid (CSF)-directed therapy may provide a means for limiting tumor recurrence. This approach has proved successful in the treatment of medulloblastoma, another brain tumor thought to be derived from stem cells. We discuss the rationale and design considerations for a clinical trial to evaluate the efficacy of CSF-directed therapy for preventing GBM recurrence.

Abstract

To determine the efficacy of motexafin gadolinium (MGd) in combination with whole brain radiotherapy (WBRT) for the treatment of brain metastases from non-small-cell lung cancer.In an international, randomized, Phase III study, patients with brain metastases from non-small-cell lung cancer were randomized to WBRT with or without MGd. The primary endpoint was the interval to neurologic progression, determined by a centralized Events Review Committee who was unaware of the treatment the patients had received.Of 554 patients, 275 were randomized to WBRT and 279 to WBRT+MGd. Treatment with MGd was well tolerated, and 92% of the intended doses were administered. The most common MGd-related Grade 3+ adverse events included liver function abnormalities (5.5%), asthenia (4.0%), and hypertension (4%). MGd improved the interval to neurologic progression compared with WBRT alone (15 vs. 10 months; p = 0.12, hazard ratio [HR] = 0.78) and the interval to neurocognitive progression (p = 0.057, HR = 0.78). The WBRT patients required more salvage brain surgery or radiosurgery than did the WBRT+MGd patients (54 vs. 25 salvage procedures, p < 0.001). A statistically significant interaction between the geographic region and MGd treatment effect (which was in the prespecified analysis plan) and between treatment delay and MGd treatment effect was found. In North American patients, where treatment was more prompt, a statistically significant prolongation of the interval to neurologic progression, from 8.8 months for WBRT to 24.2 months for WBRT+MGd (p = 0.004, HR = 0.53), and the interval to neurocognitive progression (p = 0.06, HR = 0.73) were observed.In the intent-to-treat analysis, MGd exhibited a favorable trend in neurologic outcomes. MGd significantly prolonged the interval to neurologic progression in non-small-cell lung cancer patients with brain metastases receiving prompt WBRT. The toxicity was acceptable.

Abstract

Glioblastomas often show activation of epidermal growth factor receptor (EGFR) and loss of PTEN (phosphatase and tensin homolog deleted on chromosome 10) tumor suppressor, but it is not known if these two genetic lesions act together to transform cells. To answer this question, we infected PTEN-/- neural precursor cells with a retrovirus encoding EGFRvIII, which is a constitutively activated receptor. EGFRvIII PTEN-/- cells formed highly mitotic tumors with nuclear pleomorphism, necrotic areas, and glioblastoma markers. The transformed cells showed increased cell proliferation, centrosome amplification, colony formation in soft agar, self-renewal, expression of the stem cell marker CD133, and resistance to oxidative stress and ionizing radiation. The RAS/mitogen-activated protein kinase (ERK) and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathways were activated, and checkpoint kinase 1 (Chk1), the DNA damage regulator, was phosphorylated at S280 by Akt, suppressing Chk1 phosphorylation at S345 in response to ionizing irradiation. The PTEN-/- cells showed low levels of DNA damage in the absence of irradiation, which was increased by EGFRvIII expression. Finally, secondary changes occurred during tumor growth in mice. Cells from these tumors showed decreased tumor latencies and additional chromosomal aberrations. Most of these tumor lines showed translocations of mouse chromosome 15. Intracranial injections of one of these lines led to invasive, glial fibrillary acidic protein-positive, nestin-positive tumors. These results provide a molecular basis for the occurrence of these two genetic lesions in brain tumors and point to a role in induction of genomic instability.

Abstract

Transplantation of neural precursor cells has been proposed as a possible approach for replacing missing or damaged central nervous system myelin. Neonatal and adult myelin-deficient shiverer (shi) mice, bearing a mutation of the myelin basic protein (MBP) gene, have been used extensively as hosts for testing cell engraftment, migration, and myelination, but relatively little progress has been made in reversing shi motor deficits. Here we describe a prenatal cell replacement strategy, showing that embryonic stem cells injected into shi blastocyst embryos can generate chimeric mice with strong and widespread immunoreactive MBP expression throughout the brain and a behavioral (motor) phenotype that appears essentially rescued.

Abstract

Although gliomas remain refractory to treatment, it is not clear whether this characteristic is fixed at the time of its origin or develops later. The authors have been using a model of neurocarcinogenesis to determine whether a time exists during a glioma's evolution during which it is detectable but still curable, thus providing a justification for exploring the clinical merits of an early detection and treatment strategy. The authors recently reported the presence of 2 distinct cellular subsets, 1 expressing nestin and the other both glial fibrillary acidic protein (GFAP) and osteopontin (OPN), within all examined gliomas that developed after in utero exposure to ethylnitrosourea.In this study, the authors used magnetic resonance (MR) imaging to assess when these 2 subpopulations appeared during glioma evolution.Using T2-weighted and diffusion-weighted MR imaging, the authors observed that gliomas grew exponentially once detected at rates that were location-dependent. Despite large differences in growth rates, however, they determined by correlating histochemistry with imaging in a second series of animals, that all lesions initially detected on T2-weighted images contained both subsets of cells. In contrast, lesions containing only nestin-positive cells, which appeared on average 40 days before detection on MR images, were not detected.The sequential appearance of first the nestin-positive cells followed several weeks later by those expressing GFAP/OPN suggests that all gliomas arise through common early steps in this model. Furthermore, the authors hypothesize that the expression of OPN, a molecule associated with cancer aggressiveness, at the time of T2-weighted detection signals a time during glioma development when the lesion becomes refractory to treatment.

Abstract

Brain metastases from systemic cancers are the most common malignant brain tumors encountered. Although prognosis remains poor, it is possible to stratify patients according to risk. Furthermore, an aggressive therapeutic approach for good-risk patients that includes a combination of either surgery or stereotactic radiosurgery (SRS) and whole brain radiation therapy (WBRT) can improve survival and decrease the risk of central nervous system progression.

Abstract

To better study early events in glioma genesis, markers that reliably denote landmarks in glioma development are needed. In the present study, we used microarray analysis to compare the gene expression patterns of magnetic resonance imaging (MRI)-localized N-ethyl-N-nitrosourea (ENU)-induced tumors in rat brains with those of uninvolved contralateral side and normal brains. Our analysis identified osteopontin (OPN) as the most up-regulated gene in glioma. Using immunohistochemistry we then confirmed OPN expression in every tumor examined (n = 17), including those with diameters as small as 300 mum. By contrast, no OPN immunostaining was seen in normal brain or in brains removed from ENU-exposed rats before the development of glioma. Further studies confirmed that OPN was co-localized exclusively in intratumoral glial fibrillary acidic protein-expressing cells and was notably absent from nestin-expressing ones. In conjunction with this, we confirmed that both normal neurosphere cells and ENU-im-mortalized subventricular zone/striatal cells produced negligible amounts of OPN compared to the established rat glioma cell line C6. Furthermore, inducing OPN expression in an immortalized cell line increased cell proliferation. Based on these findings, we conclude that OPN overexpression in ENU-induced gliomas occurs within a specific subset of intratumoral glial fibrillary acidic protein-positive cells and becomes evident at the stage of tumor progression.

Abstract

Pre-existing and acquired drug resistance are major obstacles to the successful treatment of glioblastomas.We used an integrated resistance model and genomics tools to globally explore molecular factors and cellular pathways mediating resistance to O6-alkylating agents in glioblastoma cells.We identified a transcriptomic signature that predicts a common in vitro and in vivo resistance phenotype to these agents, a proportion of which is imprinted recurrently by gene dosage changes in the resistant glioblastoma genome. This signature was highly enriched for genes with functions in cell death, compromise, and survival. Modularity was a predominant organizational principle of the signature, with functions being carried out by groups of interacting molecules in overlapping networks. A highly significant network was built around nuclear factor-kappaB (NF-kappaB), which included the persistent alterations of various NF-kappaB pathway elements. Tumor necrosis factor-alpha-induced protein 3 (TNFAIP3) was identified as a new regulatory component of a putative cytoplasmic signaling cascade that mediates NF-kappaB activation in response to DNA damage caused by O6-alkylating agents. Expression of the corresponding zinc finger protein A20 closely mirrored the expression of the TNFAIP3 transcript, and was inversely related to NF-kappaB activation status in the resistant cells. A prediction model based on the resistance signature enabled the subclassification of an independent, validation cohort of 31 glioblastomas into two outcome groups (P = .037) and revealed TNFAIP3 as part of an optimized four-gene predictor associated significantly with patient survival (P = .022).Our results offer strong evidence for TNFAIP3 as a key regulator of the cytoplasmic signaling to activate NF-kappaB en route to O6-alkylating agent resistance in glioblastoma cells. This pathway may be an attractive target for therapeutic modulation of glioblastomas.

Abstract

Gene expression profiling has proven useful in subclassification and outcome prognostication for human glial brain tumors. The analysis of biological significance of the hundreds or thousands of alterations in gene expression found in genomic profiling remains a major challenge. Moreover, it is increasingly evident that genes do not act as individual units but collaborate in overlapping networks, the deregulation of which is a hallmark of cancer. Thus, we have here applied refined network knowledge to the analysis of key functions and pathways associated with gliomagenesis in a set of 50 human gliomas of various histogenesis, using cDNA microarrays, inferential and descriptive statistics, and dynamic mapping of gene expression data into a functional annotation database. Highest-significance networks were assembled around the myc oncogene in gliomagenesis and around the integrin signaling pathway in the glioblastoma subtype, which is paradigmatic for its strong migratory and invasive behavior. Three novel MYC-interacting genes (UBE2C, EMP1, and FBXW7) with cancer-related functions were identified as network constituents differentially expressed in gliomas, as was CD151 as a new component of a network that mediates glioblastoma cell invasion. Complementary, unsupervised relevance network analysis showed a conserved self-organization of modules of interconnected genes with functions in cell cycle regulation in human gliomas. This approach has extended existing knowledge about the organizational pattern of gene expression in human gliomas and identified potential novel targets for future therapeutic development.

Abstract

High-resolution genome-wide mapping of exact boundaries of chromosomal alterations should facilitate the localization and identification of genes involved in gliomagenesis and may characterize genetic subgroups of glial brain tumors. We have done such mapping using cDNA microarray-based comparative genomic hybridization technology to profile copy number alterations across 42,000 mapped human cDNA clones, in a series of 54 gliomas of varying histogenesis and tumor grade. This gene-by-gene approach permitted the precise sizing of critical amplicons and deletions and the detection of multiple new genetic aberrations. It has also revealed recurrent patterns of occurrence of distinct chromosomal aberrations as well as their interrelationships and showed that gliomas can be clustered into distinct genetic subgroups. A subset of detected alterations was shown predominantly associated with either astrocytic or oligodendrocytic tumor phenotype. Finally, five novel minimally deleted regions were identified in a subset of tumors, containing putative candidate tumor suppressor genes (TOPORS, FANCG, RAD51, TP53BP1, and BIK) that could have a role in gliomagenesis.

Abstract

Sufficient quantity of genomic DNA can be a bottleneck in genome-wide analysis of clinical tissue samples. DNA polymerase Phi29 can be used for the random-primed amplification of whole genomes, although the amplification may introduce bias in gene dosage. We have performed a detailed investigation of this technique in archival fresh-frozen and formalin-fixed/paraffin-embedded tumor DNA by using cDNA microarray-based comparative genomic hybridization. Phi29 amplified DNA from matched pairs of fresh-frozen and formalin-fixed/paraffin-embedded tumor samples with similar efficiency. The distortion in gene dosage representation in the amplified DNA was nonrandom and reproducibly involved distinct genomic loci. Regional amplification efficiency was significantly linked to regional GC content of the template genome. The biased gene representation in amplified tumor DNA could be effectively normalized by using amplified reference DNA. Our data suggest that genome-wide gene dosage alterations in clinical tumor samples can be reliably assessed from a few hundred tumor cells. Therefore, this amplification method should lend itself to high-throughput genetic analyses of limited sources of tumor, such as fine-needle biopsies, laser-microdissected tissue, and small paraffin-embedded specimens.

Abstract

Brain tumors, including gliomas, develop several months after rats are exposed in utero to N-ethyl-N-nitroso-urea (ENU). Although pathological changes cannot be detected until these animals are several weeks old, the process that eventually leads to glioma formation must begin soon after exposure given the rapid clearance of the carcinogen and the observation that transformation of brain cells isolated soon after exposure occasionally occurs. This model can therefore potentially provide useful insights about the early events that precede overt glioma formation. The authors hypothesized that future glioma cells arise from stem/progenitor cells residing in or near the subventricular zone (SVZ) of the brain.Cells obtained from the SVZ or corpus striatum in ENU-exposed and control rats were cultured in an epidermal growth factor (EGF)-containing, chemically defined medium. Usually, rat SVZ cells cultured in this manner (neurospheres) are nestin-positive, undifferentiated, and EGF-dependent and undergo cell senescence. Consistent with these prior observations, control SVZ cells undergo senescence by the 12th to 15th doubling (20 of 20 cultures). In contrast, three of 15 cultures of cells derived from the SVZs of individual ENU-treated rats continue to proliferate for more than 60 cell passages. Each of these nestin-expressing immortalized cell lines harbored a common homozygous deletion spanning the INK4a/ARF locus and was unable to differentiate into neural lineages after exposure to specific in vitro stimuli. Nevertheless, unlike the rat C6 glioma cell line, these immortalized cell lines demonstrate EGF dependence and low clonogenicity in soft agar and did not form tumors after intracranial transplantation.Data in this study indicated that immortalized cells may represent glioma precursors that reside in the area of the SVZ after ENU exposure that may serve as a reservoir for further genetic and epigenetic hits that could eventually result in a full glioma phenotype.

Prevention and treatment of central nervous system involvement by non-Hodgkin's lymphoma: A review of the literatureSEMINARS IN NEUROLOGYColocci, N., Glantz, M., Recht, L.2004; 24 (4): 395-404

Abstract

Direct invasion of the central nervous system (CNS) occurs in 5% of all patients with non-Hodgkin's lymphoma, either at the time of presentation, as a solitary site of relapse, or during the course of progressive disease. Over the last several years, several studies, mostly retrospective, have analyzed risk factors associated with this complication as well as various methods to both treat and prevent it. A systematic review of the literature reveals that although a profile of a patient at particularly high risk for developing disease can be identified, treatments are for the most part ineffective at improving survival in patients with CNS lymphoma, and there is no high-quality evidence that prophylaxis prevents its occurrence. A randomized controlled trial to assess the value of prophylaxis in this disease is warranted, and suggestions for how such a trial might be designed are included in this review.

Treatment of neoplastic meningitis: what is the standard of care?Expert review of neurotherapeuticsRecht, L., Phuphanich, S.2004; 4 (4): S11-7

Abstract

This discussion will focus on defining the standard of care for neoplastic meningitis, including: What is the role of radiation therapy? What are first-line pharmacotherapeutic agents? Is combination therapy useful? What is the role of corticosteroids?

Abstract

Nestin is a unique intermediate filament protein. While it is robustly expressed in developing brain, postnatal expression is limited to the brain's subventricular zone (SVZ) and endothelial cells. Reexpression occurs, however, under several pathological conditions, including injury and neoplasia. We hypothesized that nestin would be a sensitive marker of early neoplasia after transplacental exposure of rats to ethylnitrosourea (ENU). Rats of various ages were administered bromodeoxyuridine (BudR) before sacrifice, and brain sections were examined for proliferative cells and several immunohistochemical markers, including nestin. Additional rats were examined after a stab wound injury to assess the expression of two of these markers, GFAP and nestin, in reactive astrocytes. All ENU-induced brain tumors (n = 9) were classified as gliomas (astrocytomas or oligoastrocytomas) based on their histology and immunophenotype. Nestin expression was noted in all tumors examined and was present in tumor cells as well as endothelial cells. During tumor development, we consistently noted nestin-expressing cells bearing multiple processes distributed throughout brain parenchyma. Both single cells and multiple cell clusters were observed as early as postnatal day 30 in all ENU-exposed brains examined (n = 11). Such distinctive nestin-expressing cells were not seen in nestin-stained control brains or ENU-exposed brains stained for GFAP or vimentin, nor was such a cell seen in a stab wound model used to assess reactive astrocytosis. While the number of these clusters was highly variable among rats, their size increased between 30 and 90 days. The data suggest that these nestin-expressing cells represent an early stage of the neoplastic process. It remains to be determined whether these cells become apparent at 30 days of age due to "dedifferentiation" of a local resident astrocyte or astrocyte precursor cell or migration of a relatively undifferentiated precursor/stem cell from the SVZ.

Abstract

Earlier studies reported that neural stem (NS) cells injected into blastocysts appeared to be pluripotent, differentiating into cells of all three germ layers. In this study, we followed in vitro green fluorescent protein (GFP)-labeled NS and embryonic stem (ES) cells injected into blastocysts. Forty-eight hours after injection, significantly fewer blastocysts contained GFP-NS cells than GFP-ES cells. By 96 hours, very few GFP-NS cells remained in blastocysts compared with ES cells. Moreover, 48 hours after injection, GFP-NS cells in blastocysts extended long cellular processes, ceased expressing the NS cell marker nestin, and instead expressed the astrocytic marker glial fibrillary acidic protein. GFP-ES cells in blastocysts remained morphologically undifferentiated, continuing to express the pluripotent marker stage-specific embryonic antigen-1. Selecting cells from the NS cell population that preferentially formed neurospheres for injection into blastocysts resulted in identical results. Consistent with this in vitro behavior, none of almost 80 mice resulting from NS cell-injected blastocysts replaced into recipient mothers were chimeric. These results strongly support the idea that NS cells cannot participate in chimera formation because of their rapid differentiation into glia-like cells. Thus, these results raise doubts concerning the pluripotency properties of NS cells.